The study of the comparative morphology of humans and mammals - laboratory animals used in experimental studies, is of great importance for improving diagnostic and therapeutic measures in clinical medicine. The study of histotopography...
moreThe study of the comparative morphology of humans and mammals - laboratory animals used in experimental studies, is of great importance for improving diagnostic and therapeutic measures in clinical medicine. The study of histotopography and morphoarchitectonics of ontogenetic transformations of the lower urinary tract of humans and laboratory mice in a comparative aspect is relevant for the development of simultaneous morphological scientific directions - tissue engineering, molecular medicine and reconstructive xenotransplantation.
Aim of the study. To determine the main patterns and chronological sequence of prenatal ontogenesis of organs and structures of the lower urinary tract of humans and laboratory mice.
Material and methods. The study was conducted on 14 series of consecutive histological sections of human embryos and pre-fetuses aged from 4 to 11 weeks of intrauterine development (IUD) and 15 series of histological sections of laboratory mouse embryos and pre-fetuses. The material was used from the collection of the Department of Histology, Cytology and Embryology of the Bukovina State Medical University. A complex of morphological research methods was applied (anthropometry, morphometry, microscopy, three-dimensional computer reconstruction, statistical analysis). To compare the periods of prenatal development of humans and laboratory mice, periodization according to the Carnegie stages (CS) was used.
Results. In both species, at the IUD stage CS 11, hematopoietic foci in the mesoderm of this provisional organ were detected. During the subsequent stages CS12-14, the epithelium lining it becomes multilayered, an increase in cell density is noted, which may be associated with the increasing functional demands placed on this structure. The features of the syntopy of the allantois at the stage CS16 of human embryos (end of the 5th week of gestation) and laboratory mouse (day 12 of gestation) are characterized by its location between the umbilical arteries, and its caudal part is connected to the urogenital sinus, which has not yet been completely separated from the rudiment of the rectum. In human and laboratory mouse embryos up to the stage of development CS23, processes of atrophy of the allantois are observed, which is transformed into a cellular cord, and together with the reduced remnant of the yolk sac is located among the structures of the umbilical cord. During the morphological analysis of the features of the development of the urinary bladder of the laboratory mouse, the ratio of the thickness of its membranes was determined using morphometry of histological preparations, as well as on 3D reconstructions of serial consecutive sections of the lower urinary tract. It was established that from the stage of development CS17 to CS23 in the laboratory mouse, the size of the urinary bladder increases 12 times. Features of the proliferation and differentiation of the muscular membrane of the urinary bladder of the laboratory mouse are observed, which are characterized by a wave-like process that begins from the cranial part of the organ laying (CS17 embryos) and is directed in the caudal direction (CS19 embryos). During the stage CS21, the development of smooth myocytes increases the total thickness of the muscular membrane. At stage CS23, all parts of the bladder of a laboratory mouse demonstrate a developed muscular coat, in which unidirectional bundles of muscle fibers can be distinguished, which indicates the beginning of the formation of muscle layers and, in particular, the bladder detrusor muscle.
Conclusions. 1. Comparison of the patterns of morphogenesis of the lower urinary tract in humans and laboratory mice using the Carnegie scale of prenatal development periods demonstrates the similarity of stage ontogenetic transformations, but at the microscopic level, differences were found that indicate a less differentiated bladder detrusor muscle and a relatively faster time of formation of the definitive structure of the urinary bladder. 2. In human and laboratory mouse embryos at the CS23 stage, the structures of the urinary bladder acquire the features of a definitive organ. 3. The general trends of differentiation of the muscular membrane of the urinary bladder of the laboratory mouse have a wave-like character: the process begins from the cranial part of the bladder lining and is directed in the caudal direction. 4. The ratio of layers of the bladder wall of a laboratory mouse at CS17 was: 55% - the lamina propria of the mucous membrane, 5% - its epithelial lamina (urothelium), 5% - the adventitia (or serous) membrane, 35% - the muscularis mucosa. At the stage of CS23, there is a decrease in the relative thickness of the adventitia (or serous) membrane and an increase in the muscularis mucosa of the bladder to 70% relative to its wall.